Excel 2007 IRibbonExtensibility:: GetCustomUI, XML Addin:
<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui">
<ribbon startFromScratch="false">
<tabs>
<tab id="MyTab" label="My Tab">
<group id="MyGroup" label="My Group">
<editBox id="MyEditBox" getText="MyEditBoxCallbackgetText" label="Editbox Label" onChange="MyEditBoxCallbackOnChange"/>
</group>
</tab>
</tabs>
</ribbon>
</customUI>